Mark McGwire crushed his most home runs in a month in July 1999 and in May 1998, with 16 home runs.

	NAME	HR	MONTH	G	AB	R	H	2B	3B	RBI	BB	HBP	SO	SB	CS	PA	TB	XBH	SH	SF	IBB	GIDP	AVG	OBP	SLG	OPS
1	Mark McGwire M. McGwire	16	July 1999	25	88	21	26	2	0	30	22	0	21	0	0	110	76	18	0	0	4	0	.295	.436	.864	1.300
2	Mark McGwire M. McGwire	16	May 1998	26	86	25	28	2	0	32	33	0	27	0	0	119	78	18	0	0	5	0	.326	.513	.907	1.420
3	Mark McGwire M. McGwire	15	September 1998	25	82	24	27	2	0	28	19	1	24	0	0	102	74	17	0	0	1	1	.329	.461	.902	1.363
4	Mark McGwire M. McGwire	15	September 1997	26	98	21	28	1	0	24	20	2	36	1	0	121	74	16	0	1	5	0	.286	.413	.755	1.168
5	Mark McGwire M. McGwire	15	May 1987	25	91	23	25	0	2	24	18	0	20	0	0	110	74	17	0	1	2	1	.275	.391	.813	1.204
6	Mark McGwire M. McGwire	14	June 1996	26	82	26	27	6	0	25	31	0	26	0	0	113	75	20	0	0	2	4	.329	.513	.915	1.428
7	Mark McGwire M. McGwire	13	May 2000	26	79	25	25	3	0	28	32	0	22	0	0	111	67	16	0	0	6	2	.316	.514	.848	1.362
8	Mark McGwire M. McGwire	13	July 1996	22	78	22	25	3	0	21	19	1	14	0	0	98	67	16	0	0	4	1	.321	.459	.859	1.318
9	Mark McGwire M. McGwire	12	September 1999	23	82	19	20	2	0	26	19	0	26	0	0	102	58	14	0	1	4	2	.244	.382	.707	1.090
10	Mark McGwire M. McGwire	12	August 1999	28	93	23	31	4	1	29	21	1	27	0	0	117	73	17	0	2	2	1	.333	.453	.785	1.238
11	Mark McGwire M. McGwire	12	September 1995	24	71	19	21	3	0	24	22	3	21	1	0	96	60	15	0	0	2	1	.296	.479	.845	1.324
12	Mark McGwire M. McGwire	11	July 2001	23	76	16	15	0	0	19	18	2	32	0	0	96	48	11	0	0	1	3	.197	.365	.632	.996
13	Mark McGwire M. McGwire	11	April 1997	26	87	15	28	8	0	25	23	1	16	1	0	112	69	19	0	1	5	4	.322	.464	.793	1.257
14	Mark McGwire M. McGwire	11	June 1995	28	90	20	25	2	0	24	24	3	17	0	1	118	60	13	0	1	2	2	.278	.441	.667	1.107
15	Mark McGwire M. McGwire	10	May 1999	27	92	19	25	4	0	27	22	0	24	0	0	115	59	14	0	1	3	3	.272	.409	.641	1.050
16	Mark McGwire M. McGwire	10	August 1998	28	90	21	26	7	0	19	31	1	39	1	0	123	63	17	0	1	3	0	.289	.472	.700	1.172
17	Mark McGwire M. McGwire	10	June 1998	24	83	20	26	3	0	19	19	3	17	0	0	105	59	13	0	0	7	1	.313	.457	.711	1.168
18	Mark McGwire M. McGwire	10	April 1998	24	84	20	26	6	0	32	27	0	28	0	0	113	62	16	0	2	2	2	.310	.469	.738	1.207
19	Mark McGwire M. McGwire	10	June 1997	27	94	12	25	6	0	19	11	2	31	0	0	108	61	16	0	1	1	0	.266	.352	.649	1.001
20	Mark McGwire M. McGwire	10	May 1995	27	85	23	26	6	0	26	21	3	13	0	0	110	62	16	0	1	0	4	.306	.455	.729	1.184
21	Mark McGwire M. McGwire	10	April 1992	22	75	20	25	5	0	17	20	2	12	0	0	98	60	15	0	1	2	1	.333	.480	.800	1.280
22	Mark McGwire M. McGwire	9	August 1997	25	76	17	16	2	0	18	23	3	25	1	0	103	45	11	0	1	3	0	.211	.408	.592	1.000
23	Mark McGwire M. McGwire	9	May 1996	26	87	19	31	6	0	22	18	2	20	0	0	107	64	15	0	0	1	2	.356	.477	.736	1.212
24	Mark McGwire M. McGwire	9	September 1987	27	99	17	37	10	0	22	14	0	21	0	0	116	74	19	0	3	1	2	.374	.440	.747	1.187
25	Mark McGwire M. McGwire	9	July 1987	25	102	14	32	4	0	27	4	4	25	1	1	111	63	13	0	1	0	0	.314	.360	.618	.978