Mini-matrices containing a model drug, diclofenac sodium, and three natural hydrophilic gum materials, namely karaya, locust bean and xanthan gums were produced. The swelling, erosion and drug release behaviour of these gums for controlled release were investigated and the kinetics analysed. The mini-matrices (4.5mm diameter and 30mg in weight) were compressed using a single punch tablet machine and contained a drug:gum ratio of 1:1.Swelling studies were performed in phosphate buffer medium (pH 7.0) at 37 o C to monitor both radial and axial swelling. The dimensional increases were recorded at regular time intervals using a photographic technique. The swelling index (δ) at time t expressed as percentage was calculated and analysed according to:δ = C 2 t n s where ns is the swelling exponent and C 2 is a constant. The drug release studies were performed using the USP XXIII basket method in phosphate buffer pH 7.0 and the results processed according to:M t M ~ = kt n where M t M ~ is the fractional drug release at time t, k is a constant and n is the release exponent.Swelling exponents (ns) for karaya, locust bean and xanthan gums were almost Case I (Fickian) with values of 0.420, 0.304 and 0.445 respectively (r > 0.99). However, the drug release exponents (n) tended toward Case II transport and were 0.731, 0.777 and 0.703 respectively (r > 0.99). The corresponding mean dissolution times (MDT) were 645, 160 and 322 minutes. Therefore, in addition to diffusional release, significant erosion of the swollen matrix produces accelerated release. The three gums show potential for use in multiple-unit oral dosage forms to achieve zero-order release kinetics.