South Africa’s data of Statistics reveals that the drop beat the market expectations of 5.55 percent year-on-year.
The report sees the rand record substantial gain against major currencies of the world.
On a month-on-month basis, inflation fell to 0.1 percent in April from 0.6 percent previously.
South African Reserve Bank is due to announce its latest interest rates and targets annual Consumer price index of between 3 and 6 percent.
Economists expect the central bank to keep the rate unchanged at 7 percent this month.