Several chemicals have been associated with risk of non-Hodgkin's lymphoma (NHL), many of which are substrates for N-acetyltransferase (NAT) and glutathione S-transferase (GST) enzymes. We investigated the association between polymorphisms in genes coding for these enzymes and NHL risk in a population-based study (389 cases and 535 controls). NAT1 slow genotype was associated with a slightly increased risk in women [odds ratios (OR) = 1·4; 95% confidence interval (CI) = 0·9–2·3], but not in men. NAT2 slow genotype was not associated with risk in either sex. The two slow genotypes of NAT1 and NAT2 combined were associated with a minor increase of risk in women (OR = 1·4; 0·8–2·4). There was no association with the GSTM1 or GSTT1 null genotype in either sex, irrespective of histological subtypes. Individuals with GSTP1 Val homozygotes had non-significant excessive risk of marginal zone lymphoma (OR = 1·8; 0·6–5·1) and ‘other’ B-cell NHLs (OR = 1·6; 0·7–3·6), but lower risk of diffuse large B-cell lymphoma (OR = 0·2; 0·1–0·96). Risk did not elevate with an increasing number of high-risk GST alleles in either sex. In summary, although NAT1, NAT2, GSTM1, GSTT1, or GSTP1 polymorphisms do not appear to be associated with NHL risk overall, there might be gender-specific and subtype-specific associations that require confirmation.