BLOCK-iT™ RNAi Designer
The easiest way to design effective RNAi molecules for great results
BLOCK-iT™ RNAi Express
Simplified online ordering of pre-designed and validated Stealth Select RNAi™ siRNA.
Synthetics for in vivo RNAi
Order made-on-demand RNAi in customizable plate format at 1nmole scale!
Target Design Options:
Stealth RNAi™ siRNA
siRNA to Stealth RNAi™ siRNA
siRNA to shRNA
Step 1: Enter an accession number or provide a nucleotide sequence
Enter only A, C, G, T, and U. See the online Help for additional information
Step 2: If you entered an accession number in Step 1, select regions for target design
Open reading frame (ORF)
Step 3: Choose database for Blast
Human - Homo sapiens
Mouse - Mus musculus
Rat - Rattus norvegicus
Cattle - Bos taurus
Pig - Sus scrofa
Dog - Canis familiaris
Frog - Xenopus laevis
Chicken - Gallus gallus
Fruitfly - Drosophila melanogaster
Worm - Caenorhabditis elegans
Zebrafish - Danio rerio
Mosquito - Anopheles gambiae
BLAST is used to compare input sequence with sequences in the database to find unique regions against which to design RNAi targets. The databases contain representative gene sequences for that species. Blast databases were updated on May 01, 2008 and the design output reflects the most up-to-date designs.
Step 4: Choose minimum and maximum G/C percentage
Minimum G/C percentage:
Maximum G/C percentage:
Step 5: Select siRNA design options and click "RNAi Design" to design siRNA.
Default motif pattern:
P: Proprietary (Recommended)
Tuschl's motif pattern:
The BLOCK-iT™ RNAi Designer is such an effective tool for design of siRNAs that if you order the two best siRNA sequences designed by the BLOCK-iT™ RNAi Designer, we guarantee that one of them will give greater than 70% knockdown of mRNA, given that transfection efficiency in your experiment is at least 80%.
If you already know your RNAi oligo sequence:
Order oligos online at
Order Custom Primers