Workers handling chemicals need to understand the risk to health involved in their work, and this requires training. In this study effectivity of concept attainment teaching methodology (CATM) as training strategy for cleaning workers was assessed. CATM was used to train workers on chemicals information and health hazards. Pictures, illustrations, and hazards/precautionary statements presentations were used in reception-based strategy, while printed pictures and information cards on chemicals health hazards were used in selection-based strategy. The experimental group was given a pre-training test which was repeated on completion of the training (post-test1). The test was repeated after a month to determine level of knowledge retention. Cleaner (n = 307) from hospitals, a municipality and from a privately-run company took part. Certified cleaners and supervisors, the control group, were also tested. The tests scores were compared to assess for learning attainment and knowledge retention. Compared mean scores showed improved scores after training. ANOVA of the group means showed the differences were statistically significant. The objectives of the training were met, and with good knowledge retention as indicated by the improved scores in the post-tests. This indicates the efficacy of the method in training cleaning workers.