Abstract: The locally well adapted cotton variety NIAB-78 was crossed with an exotic line REBA-288 with male parent pollen irradiated at 10 Gy of gamma rays before cross-pollinations to develop M0 seed. The M2 population was grown from M1 seed and different desirable mutants having higher yield, early maturity, short internode, resistant to CLCuV disease etc. were selected. These mutants were evaluated for yield potential and other economic traits in different segregated generations till uniformity was achieved. Of these the mutant PIM-76-8, later named as NIAB-98 was finally selected. The mutant NIAB-98 has a medium sized plant with suitable plant type and better leaf foliage. It is moderately hairy, early maturing, heat tolerant, has high yield potential and has acceptable fibre characteristics. At NIAB on the average, NIAB -98 gave 35.1 % higher yield than CIM-443, 9.1% higher yield than NIAB-Karishma, 35.8 % higher yield than CIM-482 respectively during the years 1998-99 to 2001-2. At farmers fields (3 years average) it gave 21.0, 16.1, 9.2 29.9 and 16.9% higher yield than CIM-443, NIAB-Karishma, CIM-482, CIM-446 and FH-900 was respectively during the years 1999-2002. In NCVT and DCR trials conducted by PCCC, Karachi and Director Cotton Research Institute Faisalabad, it showed wider adaptability right from Faisalabad down towards Sindh by ranking 4th in the NCVT -2000-2001 and in the DCR trials ranked 7th during 2000-2001 and 2nd during 2001-2002 respectively in the said trials. Moreover it showed early maturity, heat tolerance, relatively better tolerance to bollworms, particularly pink bollworm. It can escape the peak attack of the same due to its early maturity. It has higher oil and protein contents i.e. 24 and 28% respectively than leading/standard cotton varieties (CIM-433, CIM-446, CIM-482, CIM-473 and FH-900).