Castor oil-based soft soaps with potassium hydroxide and naturally available materials such as botanicals and preservatives that varied from soap to soap have been developed recently by the Department of Plant Protection, Agricultural College and Research Institute, Killikulam. They were evaluated against Polyphagotarsonemus latus (Banks) on chilli under both screenhouse (during 2007-2008) and field conditions (during 2008-2009). They were applied at 2.0 per cent dosage at regular intervals and P. latus incidence and damage were assessed. The results indicated that soft soap: 1 & 4 were most effective under screenhouse conditions by reducing the mite numbers up to 69.3 per cent when compared to that on control plants as against 92.8 per cent by avermectin. Under field conditions soft soap: 1 and 3 were significantly more effective than other soaps. The typical mite injured plants were nil in soft soap: 1, 2 and 5 treated plots as in avermectin plots.