Prior research shows that stimulant use is consistently associated with high-risk sexual behavior in samples of men who have sex with men (MSM), but few studies have explored factors associated with use of crack or methamphetamine during sex during specific sexual events among older, very low-income MSM. This study examined stimulant use during the most recent sexual episodes in a sample of primarily older, very low-income MSM (n=779). Although crack use was more prevalent than methamphetamine use (33% vs. 22%), findings suggest that methamphetamine users may be at greater risk for HIV transmission. HIV prevalence was higher among methamphetamine users (49%) than among crack users (24%). Having unprotected sex (OR 2.77, 95% CI 1.46-5.26), having sex in a public sex venue (OR 3.63, 95% CI 1.52-8.64), having sex with an HIV positive rather than with an HIV negative partner (OR 6.15, 95% CI 2.14-17.62), having exchanged sex for money or drugs (OR 4.16, 95% CI 1.78-9.72), and having a higher number of sexual partners (OR 1.67, 95% CI 1.17-2.38) all were associated with increased odds of methamphetamine use during sex. Fewer high-risk behaviors were associated with increased odds of using crack during sex. Having unprotected sex was associated with increased odds of crack use during sex only when sex partners were perceived to be HIV negative rather than to be HIV positive or of unknown status. Findings provide observations on associations between stimulant use during sex and risk behaviors that may be important to HIV prevention and drug treatment approaches for urban, older, very poor MSM.