Between the 1990 and 1999 seasons, Frank Thomas had the best on-base percentage, with an on-base percentage of .440.

Interpreted as:

highest obp with a minimum of 1.55 PA per team game by a player in the 1990s

	NAME	OBP	G	AB	R	H	2B	3B	HR	RBI	BB	HBP	SO	SB	CS	PA	TB	XBH	SH	SF	IBB	GIDP	AVG	SLG	OPS	WRC	WRAA	WOBA	WRC+	BRAA
1	Frank Thomas F. Thomas	.440	1,371	4,892	968	1,564	317	10	301	1,040	1,076	41	741	28	18	6,091	2,804	628	0	82	133	152	.320	.573	1.013	1257	518.8	.433	166	505.9
2	Barry Bonds B. Bonds	.434	1,434	4,894	1,091	1,478	299	42	361	1,076	1,146	45	747	343	94	6,146	2,944	702	1	60	257	96	.302	.602	1.036	1270	528.6	.434	172	538.6
3	Edgar Martinez E. Martinez	.430	1,295	4,630	854	1,492	358	12	196	750	854	56	708	38	26	5,587	2,462	566	7	40	70	125	.322	.532	.962	1093	416.7	.419	155	388.1
4	Jeff Bagwell J. Bagwell	.416	1,317	4,759	921	1,447	314	21	263	961	885	82	906	158	58	5,800	2,592	598	3	71	121	127	.304	.545	.961	1104	396.6	.412	158	421.2
5	Jim Thome J. Thome	.412	916	3,077	609	883	181	16	196	579	646	29	882	16	11	3,782	1,684	393	1	29	50	64	.287	.547	.959	724	251.1	.412	145	223.6
6	Rickey Henderson R. Henderson	.412	1,261	4,387	932	1,213	211	13	140	459	976	53	736	463	114	5,452	1,870	364	9	27	29	66	.276	.426	.838	887	228.3	.381	136	234.2
7	Bobby Abreu B. Abreu	.412	377	1,253	209	390	75	19	40	194	216	4	297	53	21	1,485	623	134	4	8	22	20	.311	.497	.909	263	75.1	.395	135	69.3
8	Mark McGwire M. McGwire	.411	1,221	4,002	791	1,071	172	1	405	956	951	52	1,040	9	5	5,054	2,460	578	2	47	118	91	.268	.615	1.025	1037	427.7	.430	166	421.9
9	John Olerud J. Olerud	.406	1,390	4,757	750	1,431	322	11	172	762	820	60	635	8	10	5,699	2,291	505	6	56	108	138	.301	.482	.888	968	277	.388	136	257.1
10	John Kruk J. Kruk	.402	708	2,437	370	746	139	23	59	375	407	2	429	30	14	2,877	1,108	221	2	29	54	58	.306	.455	.856	460	127.7	.379	136	120
11	Gary Sheffield G. Sheffield	.401	1,189	4,197	733	1,235	222	16	227	763	723	68	510	143	64	5,054	2,170	465	5	61	78	97	.294	.517	.918	900	286.7	.398	146	291.3
12	Brian Giles B. Giles	.401	440	1,378	259	407	81	7	78	272	250	7	219	32	10	1,660	736	166	4	21	21	37	.295	.534	.935	301	91.1	.400	136	79
13	Lenny Dykstra L. Dykstra	.400	644	2,521	476	751	157	23	47	232	422	20	261	152	36	2,982	1,095	227	3	16	43	20	.298	.434	.835	465	114.4	.373	130	105
14	Manny Ramirez M. Ramirez	.399	849	3,031	573	932	203	9	198	682	455	34	663	27	23	3,563	1,747	410	2	41	38	89	.307	.576	.975	690	240.3	.414	145	213.3
15	Jason Kendall J. Kendall	.399	501	1,715	281	535	115	15	31	207	173	89	166	71	16	2,004	773	161	6	21	19	32	.312	.451	.850	322	69.6	.375	124	61.2
16	Dave Magadan D. Magadan	.394	1,062	3,001	381	866	154	9	31	359	540	8	404	10	10	3,609	1,131	194	21	39	33	76	.289	.377	.771	502	71.6	.352	117	72.5
17	Chipper Jones C. Jones	.394	779	2,890	542	871	166	17	153	524	459	3	463	83	19	3,386	1,530	336	3	31	28	80	.301	.529	.923	608	180.7	.397	140	174
18	Rusty Greer R. Greer	.393	809	2,991	516	923	192	20	103	503	422	18	445	25	12	3,469	1,464	315	5	33	14	67	.309	.489	.883	589	150.9	.386	125	115.7
19	Tim Salmon T. Salmon	.393	955	3,483	608	1,015	195	14	196	660	579	31	820	29	31	4,139	1,826	405	0	46	29	45	.291	.524	.917	736	220.2	.396	136	194.9
20	Tony Phillips T. Phillips	.392	1,326	5,029	946	1,374	253	25	127	560	977	31	1,009	121	72	6,103	2,058	405	26	40	39	82	.273	.409	.801	906	172.2	.363	119	143.1
21	Brett Butler B. Butler	.392	1,013	3,801	617	1,143	108	57	18	260	565	19	442	251	116	4,492	1,419	183	82	25	10	25	.301	.373	.765	621	93	.351	120	106.7
22	Mike Piazza M. Piazza	.391	981	3,653	611	1,200	173	4	240	768	381	13	563	13	13	4,075	2,101	417	0	28	83	114	.328	.575	.966	770	261.1	.409	154	281.7
23	Jack Clark J. Clark	.390	336	1,072	166	263	41	2	58	182	256	7	311	5	6	1,347	482	101	0	12	17	33	.245	.450	.840	212	62.1	.377	132	49.8
24	Larry Walker L. Walker	.390	1,278	4,545	882	1,423	314	36	262	851	527	79	794	189	55	5,201	2,595	612	4	46	81	98	.313	.571	.961	980	353.8	.410	141	268
25	Randy Milligan R. Milligan	.390	536	1,670	239	437	78	5	55	231	352	9	331	6	11	2,045	690	138	0	14	8	53	.262	.413	.803	306	74.8	.367	128	67.5